SUPPRESSION OF LOW-FREQUENCY STRUCTURAL VIBRATIONS USING INTELLIGENT CONTROL METHODS

To suppress the low frequency vibration of Large Space Structures, the possibility of using a proof-mass based actuator is discussed. In ord er to avoid instabilities caused by the effect of the actuator's own n atural frequency on the low frequency components of the structural vib ration, it is proposed that the only control force be the electromagne tic force generated by the actuator and that there be no mechanical sp ring between the moving and the fixed parts of the actuator. In this c onfiguration, it is easy for the moving mass of the actuator to exceed the stroke limit, so the actuator must be controlled to avoid these l imits. Using the proposed actuator, three kinds of intelligent control , methods are considered in order to achieve reliable control of the l ow frequency vibrations: fuzzy control, dithered fuzzy control, and ru le based crisp control. Simulation results show the effectiveness of t he proposed control algorithms.